An explosively formed projectile or penetrator (EFP) uses an explosive energy to deform a metal plate into a coherent penetrator while simultaneously accelerating the coherent penetrator to extremely high velocities, employing a kinetic energy penetrator without the necessity of a large gun. A conventional explosively formed projectile is comprised of one or more metallic liners, a case, an explosive section, and an initiation train. Typically, the explosively formed projectile comprises a retaining ring to position and hold the liner-explosive subassembly in place. Explosively formed projectiles produce one or more massive, high velocity penetrators. After detonation, the explosive products create enormous pressures that accelerate one or more liners while simultaneously reshaping the liners into a rod or some other desired shape. The explosively formed penetrator then impacts the target at a high speed, delivering significantly high mechanical power.
An EFP warhead configuration typically comprises a steel case, a high-explosive charge, and a metallic liner. Explosively formed projectile warheads have been designed to project one or more high velocity projectiles to attack armored targets. Currently, each type of EFP warhead is designed for a specific set of targets and a specific lethality range. For example, a larger, more massive EFP warhead is used for heavily armored targets such as tanks, while lightly armored targets require a smaller, less massive EFP.
The overall limited functionality of an EFP warhead requires duplication of munitions during deployment, increasing the complexity of planning for a deployment, decreasing the number of each type of EFP warhead required, and increasing the complexity of engaging an enemy.
Conventional EFP warhead configurations comprise fragmentation techniques to expand the set of targets for a specific EFP warhead. Although this technology has proven to be useful, it would be desirable to present additional improvements. One fragmentation technique requires intricate forming or machining of the metallic liner to form, when exploded, a center slug with a concentric ring of fragments. Although the lighter weight fragments formed by this EFP warhead are suitable for softer targets, this approach reduces the amount of mass available for the center slug, reducing the lethality against harder targets. In this approach, the fragmentation pattern is fixed during manufacture and cannot be changed during deployment.
Another fragmentation technique places a large mesh screen in front of the metallic liner. When exploded, the metallic liner impacts and passes through the screen, fragmenting the metallic liner. This approach allows a specific EFP warhead to be deployed, without the screen, against a heavily armored target and, with the screen, against a softer target. However a complex release mechanism is required to release the screen when the screen is not desired.
Fragmentation techniques are also used on munitions casings to generate case fragmentation during deployment of a munition, increasing the effectiveness of the munition against a variety of targets. Although this technology has proven to be useful, it would be desirable to present additional improvements. Conventional techniques for producing case fragmentation require a multi-step process that can be complex and costly. In one approach, a flat metal sheet is embossed and formed into the cylindrical portion of the casing. In another approach, the cylindrical portion of the casing is broached in a complex two-step process. In both approaches, the fragmentation pattern is fixed during manufacture and cannot be changed during deployment to meet the lethality requirements of a variety of targets.
What is therefore needed is a fragmentation technique that introduces versatility and selectivity in the output of an EFP warhead or munition casing, providing an EFP warhead or munition with variable and selectable lethality for deployment against a variety of targets. Thus, there is a need for a system and method for explosively stamping a selective fragmentation pattern. The need for such a system has heretofore remained unsatisfied.